Re: [PATCH 5/6] ARM: shmobile: lager: Set sdhi and mmcif clock rates

[Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>]

On Mon, 2015-05-18 at 20:48 +0100, Ben Hutchings wrote:
> On Sun, 2015-05-17 at 10:13 +0200, Geert Uytterhoeven wrote:
> > On Sun, May 17, 2015 at 2:29 AM, Ben Hutchings
> > <ben.hutchings@xxxxxxxxxxxxxxx> wrote:
> > > From: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx>
> > >
> > > [bwh: Fold in fix from Ian Molton]
> > > Signed-off-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
> > > ---
> > >  arch/arm/boot/dts/r8a7790-lager.dts |   11 +++++++++++
> > >  1 file changed, 11 insertions(+)
> > >
> > > diff --git a/arch/arm/boot/dts/r8a7790-lager.dts b/arch/arm/boot/dts/r8a7790-lager.dts
> > > index aaa4f258e279..343ec0ccc8df 100644
> > > --- a/arch/arm/boot/dts/r8a7790-lager.dts
> > > +++ b/arch/arm/boot/dts/r8a7790-lager.dts
> > > @@ -413,6 +413,11 @@
> > >         vmmc-supply = <&fixedregulator3v3>;
> > >         bus-width = <8>;
> > >         non-removable;
> > > +
> > > +       assigned-clocks = <&mstp3_clks R8A7790_CLK_MMCIF1>;
> > > +       assigned-clock-rates = <97500000>;
> > > +       max-frequency = <50000000>;
> > 
> > Are all these properties Lager-specific, or r8a7790-specific?
> > If the latter, they belong in r8a7790.dtsi.
> > Same comment for the other nodes.
> 
> The clock assignments are not specific to Lager so they probably belong
> in r8a7790.dtsi; the dividers are configurable and could be
> board-specific.

The problem with doing that is I think the assigned-clocks and
assigned-clock-rates properties belong together.  I can't find any other
instance where they are split between a .dtsi file and .dts files that
include it.

I *could* define both properties in r8a7790.dtsi and then let board .dts
files override the clock rate if wanted.

> The board design could conceivably limit the usable frequency to below
> the chip's maximum, though presumably that won't usually happen.
> Currently the clk-rcar-gen2 driver only configures the dividers for
> sdhi{0,1}.  That leaves the rest of them effectively controlled by the
> board's firmware.

I was mistaken about this; the other dividers are programmed by
clk-div6.

Ben.


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